1. Field of the Invention
The present invention relates to underground continuous wall building method and apparatus for building a variety of continuous walls in the ground for water cutoff purpose, reinforcing purpose and other purposes.
2. Description of Background Art
As a technique for building an underground continuous wall, there has been conventionally known a method according to which a chain cutter is vertically mounted on a running carriage (e.g. a base machine of a crawler crane), the running carriage is moved in a transverse direction while the cutter is rotated, thereby excavating a continuous trench of a fixed width, and a continuous wall is built by pouring a wall material such as cement or concrete into this continuous trench and solidifying it therein or by inserting a concrete panel therein (refer to Japanese Unexamined Patent Publication Nos. 5(HEI)-280043 and 5(HEI)-280044.
The cutter is constructed such that an endless chain is fitted between upper and bottom ends of a cutter post which is a vertically long boxlike frame, and a continuous trench Gis excavated by a multitude of excavating blades provided at the outer surface of the chain.
However, according to this technique, only vertically extending continuous walls can be built. Therefore, such walls cannot have a water cutoff function along vertical direction as cutoff walls, but can only be used as cutoff walls along horizontal direction.
Thus, in the case that a water cutoff function along vertical direction is required, the ground must be filled up after being excavated to built a horizontal cutoff wall or a vertical wall must be built up to an impermeable bed. However, such techniques are poor in performance and high in cost.